On Tue, Aug 11, 2009 at 7:14 PM, Jens Axboe<jens.axboe@xxxxxxxxxx> wrote: > On Tue, Aug 11 2009, Bart Van Assche wrote: >> On Tue, Aug 11, 2009 at 4:39 PM, Jens Axboe<jens.axboe@xxxxxxxxxx> wrote: >> > On Tue, Aug 11 2009, Bart Van Assche wrote: >> >> On Thu, Aug 6, 2009 at 9:58 PM, Jens Axboe <jens.axboe@xxxxxxxxxx> wrote: >> >> > Anyway, YMMV, I would appreciate some test results (and as usual, that >> >> > even includes just saying that it boots and functions for you). If >> >> > people feel adventurous, patches for other controllers will be happily >> >> > queued up for testing. I may even be convinced to implement support >> >> > for your controller of choice, if you have some fast storage hooked up >> >> > and would like to experiment. Generally, adding support to a driver is >> >> > not very hard and the two conversions included were also meant to serve >> >> > as an inspiration. >> >> >> >> Sounds very interesting. Have you already considered patching the SRP >> >> initiator ? During the SRP performance tests I ran CPU usage on the >> >> initiator was more than 95% and on the target less than 10%. >> > >> > No I haven't, if you point me at which srp files, I can take a look. >> >> The relevant source files are: >> include/scsi/srp.h >> include/scsi/scsi_transport_srp.h >> drivers/infiniband/ulp/srp/ib_srp.h >> drivers/infiniband/ulp/srp/ib_srp.c >> drivers/scsi/scsi_transport_srp.c >> drivers/scsi/libsrp.c >> drivers/scsi/scsi_transport_srp_internal.h > > I can find | grep too :-) The command "find | grep srp" would have returned a few more source files. The most relevant starting point is the source file drivers/infiniband/ulp/srp/ib_srp.c, which contains the struct scsi_host_template. > Did you profile this? Where did it burn all the CPU time on the > initiator side? The test I ran involved a Linux SRP initiator and a Linux SRP target (SCST) using a RAM disk as backstorage. Read throughput is about 1700 MB/s for block sizes of 8 MB and above. But with a block size of 4 KB, the read throughput on the initiator drops to 100 MB/s. At this block size there are about 50.000 interrupts per second generated by the InfiniBand HCA in the initiator system. On the same setup the ib_send_bw tool reports a throughput of 1850 MB/s for a block size of 4 KB. This last tool is not interrupt driven but uses polling. Bart. -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
